Publications

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rapid extirpation of a north american frog coincides with an increase in fungal pathogen prevalence: historical analysis and implications for reintroduction.as extinctions continue across the globe, conservation biologists are turning to species reintroduction programs as one optimistic tool for addressing the biodiversity crisis. for repatriation to become a viable strategy, fundamental prerequisites include determining the causes of declines and assessing whether the causes persist in the environment. invasive species-especially pathogens-are an increasingly significant factor contributing to biodiversity loss. we hypothesized that batrachochytriu ...201729238549
composition of micro-eukaryotes on the skin of the cascades frog (rana cascadae) and patterns of correlation between skin microbes and batrachochytrium dendrobatidis.global amphibian decline linked to fungal pathogens has galvanized research on applied amphibian conservation. skin-associated bacterial communities of amphibians have been shown to mediate fungal skin infections and the development of probiotic treatments with antifungal bacteria has become an emergent area of research. while exploring the role of protective bacteria has been a primary focus for amphibian conservation, we aim to expand and study the other microbes present in amphibian skin comm ...201729276502
correction: introduced bullfrogs are associated with increased batrachochytrium dendrobatidis prevalence and reduced occurrence of korean treefrogs.[this corrects the article doi: 10.1371/journal.pone.0177860.].201729284040
comparison of methods for detection of chytrid fungus (batrachochytrium dendrobatidis) in bullfrog tadpole mouthparts.we previously reported that the tadpole of bullfrog (lithobates catesbeiana) is a useful model for the field surveillance of the batrachochytrium dendrobatidis (bd) distribution. in the present study, we compared bd detection rates in swab-scraped and resected mouthpart samples, using nested polymerase chain reaction (pcr). the resulting detection rates for swab-scraped and resected specimens were 67% and 65%, respectively, with no significant difference. furthermore, we performed a histopatholo ...201729269708
perspectives on invasive amphibians in brazil.introduced species have the potential to become invasive and jeopardize entire ecosystems. the success of species establishing viable populations outside their original extent depends primarily on favorable climatic conditions in the invasive ranges. species distribution modeling (sdm) can thus be used to estimate potential habitat suitability for populations of invasive species. here we review the status of six amphibian species with invasive populations in brazil (four domestic species and two ...201728938024
cryptic disease-induced mortality may cause host extinction in an apparently stable host-parasite system.the decline of wildlife populations due to emerging infectious disease often shows a common pattern: the parasite invades a naive host population, producing epidemic disease and a population decline, sometimes with extirpation. some susceptible host populations can survive the epidemic phase and persist with endemic parasitic infection. understanding host-parasite dynamics leading to persistence of the system is imperative to adequately inform conservation practice. here we combine field data, s ...201728954907
efficacy of chemical disinfectants for the containment of the salamander chytrid fungus batrachochytrium salamandrivorans.the recently emerged chytrid fungus batrachochytrium salamandrivorans (bsal) causes european salamander declines. proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. here, the efficacy of chemical disinfectants in killing bsal was evaluated. at all tested conditions, biocidal®, chloramine-t®, dettol medical®, disolol®, ethanol, f10®, hibiscrub®, potassium permanganate, safe4®, sodium hypochlorite, and virkon s®, were effective at killing bsal. ...201729023562
skin bacterial microbiome of a generalist puerto rican frog varies along elevation and land use gradients.host-associated microbial communities are ubiquitous among animals, and serve important functions. for example, the bacterial skin microbiome of amphibians can play a role in preventing or reducing infection by the amphibian chytrid fungus, batrachochytrium dendrobatidis. evidence suggests that environmental bacteria likely serve as a source pool for at least some of the members of the amphibian skin bacterial community, underscoring the potential for local environmental changes to disrupt micro ...201728875068
temporal variation of the skin bacterial community and batrachochytrium dendrobatidis infection in the terrestrial cryptic frog philoria loveridgei.in animals and plants, symbiotic bacteria can play an important role in disease resistance of host and are the focus of much current research. globally, amphibian population declines and extinctions have occurred due to chytridiomycosis, a skin disease caused by the pathogen batrachochytrium dendrobatidis (bd). currently amphibian skin bacteria are increasingly recognized as important symbiont communities with a relevant role in the defense against pathogens, as some bacteria can inhibit the gro ...201729312226
design- and model-based recommendations for detecting and quantifying an amphibian pathogen in environmental samples.accurate pathogen detection is essential for developing management strategies to address emerging infectious diseases, an increasingly prominent threat to wildlife. sampling for free-living pathogens outside of their hosts has benefits for inference and study efficiency, but is still uncommon. we used a laboratory experiment to evaluate the influences of pathogen concentration, water type, and qpcr inhibitors on the detection and quantification of batrachochytrium dendrobatidis (bd) using water ...201729299272
are the adverse effects of stressors on amphibians mediated by their effects on stress hormones?adverse effects of anthropogenic changes on biodiversity might be mediated by their impacts on the stress response of organisms. to test this hypothesis, we crossed exposure to metyrapone, a synthesis inhibitor of the stress hormone corticosterone, with exposure to the herbicide atrazine and the fungal pathogen batrachochytrium dendrobatidis (bd) to assess whether the effects of these stressors on tadpoles and post-metamorphic frogs were mediated by corticosterone. metyrapone countered atrazine- ...201729222721
probiotic consortia are not uniformly effective against different amphibian chytrid pathogen isolates.symbiotic bacterial communities can protect their hosts from infection by pathogens. treatment of wild individuals with protective bacteria (probiotics) isolated from hosts can combat the spread of emerging infectious diseases. however, it is unclear whether candidate probiotic bacteria can offer consistent protection across multiple isolates of globally distributed pathogens. here, we use the lethal amphibian fungal pathogen batrachochytrium dendrobatidis to investigate whether probiotic richne ...201729218845
low resistance to chytridiomycosis in direct-developing amphibians.host-generalist pathogens sporadically infect naive hosts, potentially triggering epizootics. the waterborne fungus batrachochytrium dendrobatidis (bd) is linked to declines of hundreds of amphibian species with aquatic larvae. although several population declines and extinctions attributed to bd have been reported among cryptic species undergoing direct development away from water, epidemiological studies focused on these terrestrial frogs are lacking. our field data support that terrestrial di ...201729192210
lowland extirpation of anuran populations on a tropical mountain.climate change and infectious diseases threaten animal and plant species, even in natural and protected areas. to cope with these changes, species may acclimate, adapt, move or decline. here, we test for shifts in anuran distributions in the luquillo mountains (lm), a tropical montane forest in puerto rico by comparing species distributions from historical (1931-1989)and current data (2015/2016).201729158987
amphibian species traits, evolutionary history and environment predict batrachochytrium dendrobatidis infection patterns, but not extinction risk.the fungal pathogen batrachochytrium dendrobatidis (b. dendrobatidis) has emerged as a major agent of amphibian extinction, requiring conservation intervention for many susceptible species. identifying susceptible species is challenging, but many aspects of species biology are predicted to influence the evolution of host resistance, tolerance, or avoidance strategies towards disease. in turn, we may expect species exhibiting these distinct strategies to differ in their ability to survive epizoot ...201729151866
batrachochytrium salamandrivorans and the risk of a second amphibian pandemic.amphibians are experiencing devastating population declines globally. a major driver is chytridiomycosis, an emerging infectious disease caused by the fungal pathogens batrachochytrium dendrobatidis (bd) and batrachochytrium salamandrivorans (bsal). bd was described in 1999 and has been linked with declines since the 1970s, while bsal is a more recently discovered pathogen that was described in 2013. it is hypothesized that bsal originated in asia and spread via international trade to europe, wh ...201729147975
prodigiosin, violacein, and volatile organic compounds produced by widespread cutaneous bacteria of amphibians can inhibit two batrachochytrium fungal pathogens.symbiotic bacteria can produce secondary metabolites and volatile compounds that contribute to amphibian skin defense. some of these symbionts have been used as probiotics to treat or prevent the emerging disease chytridiomycosis. we examined 20 amphibian cutaneous bacteria for the production of prodigiosin or violacein, brightly colored defense compounds that pigment the bacteria and have characteristic spectroscopic properties making them readily detectable, and evaluated the antifungal activi ...201729119317
amphibian skin defences show variation in ability to inhibit growth of batrachochytrium dendrobatidis isolates from the global panzootic lineage.the fungal pathogen batrachochytrium dendrobatidis has caused declines and extinctions in hundreds of amphibian species across the world. virulence varies among and within lineages; the global panzootic lineage (gpl) is the most pathogenic, although there is also variation in lethality among gpl isolates. amphibians have a number of defences against pathogens, and skin products including the microbiota and host peptides have considerable influence over disease progression. here we demonstrate th ...201729095686
prevalence and genetic diversity of batrachochytrium dendrobatidis in central african island and continental amphibian communities.the fungal pathogen batrachochytrium dendrobatidis (bd) infects hundreds of amphibian species and is implicated in global amphibian declines. bd is comprised of several lineages that differ in pathogenicity, thus, identifying which bd strains are present in a given amphibian community is essential for understanding host-pathogen dynamics. the presence of bd has been confirmed in central africa, yet vast expanses of this region have not yet been surveyed for bd prevalence, and the genetic diversi ...201729043029
epizootic to enzootic transition of a fungal disease in tropical andean frogs: are surviving species still susceptible?the fungal pathogen batrachochytrium dendrobatidis (bd), which causes the disease chytridiomycosis, has been linked to catastrophic amphibian declines throughout the world. amphibians differ in their vulnerability to chytridiomycosis; some species experience epizootics followed by collapse while others exhibit stable host/pathogen dynamics where most amphibian hosts survive in the presence of bd (e.g., in the enzootic state). little is known about the factors that drive the transition between th ...201729040327
do host-associated gut microbiota mediate the effect of an herbicide on disease risk in frogs?environmental stressors, such as pollutants, can increase disease risk in wildlife. for example, the herbicide atrazine affects host defences (e.g. resistance and tolerance) of the amphibian chytrid fungus batrachochytrium dendrobatidis (bd), but the mechanisms for these associations are not entirely clear. given that pollutants can alter the gut microbiota of hosts, which in turn can affect their health and immune systems, one potential mechanism by which pollutants could increase infection ris ...201729030867
batrachochytrium salamandrivorans not detected in u.s. survey of pet salamanders.we engaged pet salamander owners in the united states to screen their animals for two amphibian chytrid fungal pathogens batrachochytrium dendrobatidis (bd) and b. salamandrivorans (bsal). we provided pet owners with a sampling kit and instructional video to swab the skin of their animals. we received 639 salamander samples from 65 species by mail, and tested them for bd and bsal using qpcr. we detected bd on 1.3% of salamanders (95% ci 0.0053-0.0267) and did not detect bsal (95% ci 0.0000-0.007 ...201729030586
estimating herd immunity to amphibian chytridiomycosis in madagascar based on the defensive function of amphibian skin bacteria.for decades, amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. madagascar is an amphibian biodiversity hotspot where batrachochytrium dendrobatidis (bd) has only recently been detected. while no bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, includ ...201728959244
detection of amphibian chytrid fungus on waterfowl integument in natural settings.the chytrid fungus batrachochytrium dendrobatidis (bd), the causal agent of the amphibian disease chytridiomycosis, has spread at an alarming rate since its discovery. bd was initially thought to only infect keratinizing epithelial cells in amphibians, a core component of amphibian skin. however, recent studies have detected bd on the integument of non-amphibian hosts. we conducted a survey of 3 duck species (gadwalls, green-winged teals, and mallards) to determine whether bd dna could be found ...201728930087
differential patterns of batrachochytrium dendrobatidis infection in relict amphibian populations following severe disease-associated declines.global amphibian biodiversity has declined dramatically in the past 4 decades, and many amphibian species have declined to near extinction as a result of emergence of the amphibian chytrid fungus, batrachochytrium dendrobatidis (bd). however, persistent or recovering populations of several amphibian species have recently been rediscovered, and such populations may illustrate how amphibian species that are highly susceptible to chytridiomycosis may survive in the presence of bd. we conducted fiel ...201728930083
the influence of temperature on chytridiomycosis in vivo.chytridiomycosis, an amphibian disease caused by the fungal pathogen batrachochytrium dendrobatidis (bd), is an ideal system for studying the influence of temperature on host-pathogen relationships because both host and pathogen are ectothermic. studies of bd in culture suggest that optimal growth occurs between 17 and 23°c, and death of the fungus occurs above 29 or below 0°c. amphibian immune systems, however, are also temperature dependent and often more effective at higher temperatures. we t ...201728879516
inhibition of fungal pathogens across genotypes and temperatures by amphibian skin bacteria.symbiotic bacteria may dampen the impacts of infectious diseases on hosts by inhibiting pathogen growth. however, our understanding of the generality of pathogen inhibition by different bacterial taxa across pathogen genotypes and environmental conditions is limited. bacterial inhibitory properties are of particular interest for the amphibian-killing fungal pathogens (batrachochytrium dendrobatidis and batrachochytrium salamandrivorans), for which probiotic applications as conservation strategie ...201728871241
white blood cell profiles in amphibians help to explain disease susceptibility following temperature shifts.temperature variability, and in particular temperature decreases, can increase susceptibility of amphibians to infections by the fungus batrachochytrium dendrobatidis (bd). however, the effects of temperature shifts on the immune systems of bd-infected amphibians are unresolved. we acclimated frogs to 16 °c and 26 °c (baseline), simultaneously transferred them to an intermediate temperature (21 °c) and inoculated them with bd (treatment), and tracked their infection levels and white blood cell p ...201728870450
first parasitological study of the african clawed frog (xenopus laevis, amphibia) in chile.introduced species can arrive into new territories with parasites; however, these species are expected to face lower parasite richness than in their original regions. both introduced hosts and parasites can affect native fauna. since their release into the wild in chile following laboratory use, xenopus laevis daudin, 1802 has widely spread throughout central chile. the only pathogen described on the host is the fungus batrachochytrium dendrobatidis longcore, pessier, nichols, 1999; thus, this i ...201728746452
using stochastic epidemiological models to evaluate conservation strategies for endangered amphibians.recent outbreaks of chytridiomycosis, the disease of amphibians caused by the fungal pathogen batrachochytrium dendrobatidis (bd), have contributed to population declines of numerous amphibian species worldwide. the devastating impacts of this disease have led researchers to attempt drastic conservation measures to prevent further extinctions and loss of biodiversity. the conservation measures can be labour-intensive or expensive, and in many cases have been unsuccessful. we developed a mathemat ...201728855388
infection increases vulnerability to climate change via effects on host thermal tolerance.unprecedented global climate change and increasing rates of infectious disease emergence are occurring simultaneously. infection with emerging pathogens may alter the thermal thresholds of hosts. however, the effects of fungal infection on host thermal limits have not been examined. moreover, the influence of infections on the heat tolerance of hosts has rarely been investigated within the context of realistic thermal acclimation regimes and potential anthropogenic climate change. we tested for ...201728839273
land cover and forest connectivity alter the interactions among host, pathogen and skin microbiome.deforestation has detrimental consequences on biodiversity, affecting species interactions at multiple scales. the associations among vertebrates, pathogens and their commensal/symbiotic microbial communities (i.e. microbiomes) have important downstream effects for biodiversity conservation, yet we know little about how deforestation contributes to changes in host microbial diversity and pathogen abundance. here, we tested the effects of landcover, forest connectivity and infection by the chytri ...201728835551
the effect of captivity on the skin microbial symbionts in three atelopus species from the lowlands of colombia and ecuador.many amphibian species are at risk of extinction in their natural habitats due to the presence of the fungal pathogen batrachochytrium dendrobatidis (bd). for the most highly endangered species, captive assurance colonies have been established as an emergency measure to avoid extinction. experimental research has suggested that symbiotic microorganisms in the skin of amphibians play a key role against bd. while previous studies have addressed the effects of captivity on the cutaneous bacterial c ...201728785515
a pesticide paradox: fungicides indirectly increase fungal infections.there are many examples where the use of chemicals have had profound unintended consequences, such as fertilizers reducing crop yields (paradox of enrichment) and insecticides increasing insect pests (by reducing natural biocontrol). recently, the application of agrochemicals, such as agricultural disinfectants and fungicides, has been explored as an approach to curb the pathogenic fungus, batrachochytrium dendrobatidis (bd), which is associated with worldwide amphibian declines. however, the lo ...201728763165
the pharmacokinetics of topical itraconazole in panamanian golden frogs (atelopus zeteki).chytridiomycosis is caused by the fungus batrachochytrium dendrobatidis and is one of the primary causes of the global decline in amphibian populations and specifically of the panamanian golden frog ( atelopus zeteki ). itraconazole has been demonstrated to be an effective treatment for chytridiomycosis by inhibiting cytochrome p450, a major enzyme important for the structure of b. dendrobatidis zoospores' plasma membranes. however, anecdotal reports of toxicity in this and other amphibian speci ...201728749305
resistance, tolerance and environmental transmission dynamics determine host extinction risk in a load-dependent amphibian disease.while disease-induced extinction is generally considered rare, a number of recently emerging infectious diseases with load-dependent pathology have led to extinction in wildlife populations. transmission is a critical factor affecting disease-induced extinction, but the relative importance of transmission compared to load-dependent host resistance and tolerance is currently unknown. using a combination of models and experiments on an amphibian species suffering extirpations from the fungal patho ...201728745026
antifungal treatment of wild amphibian populations caused a transient reduction in the prevalence of the fungal pathogen, batrachochytrium dendrobatidis.emerging infectious diseases can drive host populations to extinction and are a major driver of biodiversity loss. controlling diseases and mitigating their impacts is therefore a priority for conservation science and practice. chytridiomycosis is a devastating disease of amphibians that is caused by the fungal pathogen batrachochytrium dendrobatidis (bd), and for which there is an urgent need to develop mitigation methods. we treated tadpoles of the common midwife toad (alytes obstetricans) wit ...201728729557
skin bacterial community reorganization following metamorphosis of the fire-bellied toad (bombina orientalis).in organisms with complex life histories, dramatic changes in microbial community structure may occur with host development and immune system maturation. amphibian host susceptibility to diseases such as chytridiomycosis may be affected by the reorganization of skin microbial community structure that occurs during metamorphosis. we tracked changes in the bacterial communities inhabiting skin of korean fire-bellied toads (bombina orientalis) that we infected as tadpoles with different strains of ...201728725944
disease-associated change in an amphibian life-history trait.emerging pathogens can drive evolutionary shifts in host life-history traits, yet this process remains poorly documented in vertebrate hosts. amphibian chytridiomycosis, caused by infection with the fungal pathogen batrachochytrium dendrobatidis (bd), is the worst recorded wildlife disease and has caused the extinction of over 100 species across multiple continents. a similar number of additional species have experienced mass declines and bd remains a major source of mortality in many population ...201728707112
host niche may determine disease-driven extinction risk.the fungal pathogen batrachochytrium dendrobatidis (bd) drives declines and extinctions in amphibian communities. however, not all regions and species are equally affected. here, we show that association with amphibian aquatic habitat types (bromeliad phytotelmata versus stream) across central america results in the odds of being threatened by bd being five times higher in stream microhabitats. this differential threat of bd was supported in our study by a significantly lower prevalence of bd in ...201728704480
major histocompatibility complex variation and the evolution of resistance to amphibian chytridiomycosis.chytridiomycosis, caused by the fungal pathogen batrachochytrium dendrobatidis (bd), has been implicated in population declines and species extinctions of amphibians around the world. susceptibility to the disease varies both within and among species, most likely attributable to heritable immunogenetic variation. analyses of transcriptional expression in hosts following their infection by bd reveal complex responses. species resistant to bd generally show evidence of stronger innate and adaptive ...201728695290
effects of host species and environment on the skin microbiome of plethodontid salamanders.the amphibian skin microbiome is recognized for its role in defence against pathogens, including the deadly fungal pathogen batrachochytrium dendrobatidis (bd). yet, we have little understanding of evolutionary and ecological processes that structure these communities, especially for salamanders and closely related species. we investigated patterns in the distribution of bacterial communities on plethodon salamander skin across host species and environments. quantifying salamander skin microbiom ...201728682480
dominance-function relationships in the amphibian skin microbiome.some amphibian skin bacteria inhibit growth of a fungal amphibian pathogen, batrachochytrium dendrobatidis (bd), but it is unclear how dominant these anti-bd bacteria are in skin communities. using in vitro co-culture challenge assays, we quantified bd inhibition by bacterial isolates collected from the skin of four amphibian species: bullfrogs, eastern newts, spring peepers and american toads. the 16s rrna sequences for each isolate were matched to culture-independent amplicon sequences from th ...201728677171
temperature variation, bacterial diversity and fungal infection dynamics in the amphibian skin.host-associated bacterial communities on the skin act as the first line of defence against invading pathogens. yet, for most natural systems, we lack a clear understanding of how temperature variability affects structure and composition of skin bacterial communities and, in turn, promotes or limits the colonization of opportunistic pathogens. here, we examine how natural temperature fluctuations might be related to changes in skin bacterial diversity over time in three amphibian populations infe ...201728664981
epidemic and endemic pathogen dynamics correspond to distinct host population microbiomes at a landscape scale.infectious diseases have serious impacts on human and wildlife populations, but the effects of a disease can vary, even among individuals or populations of the same host species. identifying the reasons for this variation is key to understanding disease dynamics and mitigating infectious disease impacts, but disentangling cause and correlation during natural outbreaks is extremely challenging. this study aims to understand associations between symbiotic bacterial communities and an infectious di ...201728637861
identification of bufadienolides from the boreal toad, anaxyrus boreas, active against a fungal pathogen.amphibian granular glands provide a wide range of compounds on the skin that defend against pathogens and predators. we identified three bufadienolides-the steroid-like compounds arenobufagin, gamabufotalin, and telocinobufagin-from the boreal toad, anaxyrus boreas, through liquid chromatography mass spectrometry (lc/ms). compounds were detected both after inducing skin gland secretions and in constitutive mucosal rinses from toads. we described the antimicrobial properties of each bufadienolide ...201728631214
skin sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen.the fungal pathogen batrachochytrium dendrobatidis (bd) has been implicated in amphibian population declines globally. given that bd infection is limited to the skin in post-metamorphic amphibians, routine skin sloughing may regulate infection. skin sloughing has been shown to reduce the number of cultivatable microbes on amphibian skin, and bd infection increases skin sloughing rates at high loads. however, it is unclear whether species specific differences in skin sloughing patterns could regu ...201728615642
four new species of terrestrial-breeding frogs of the genus <i>phrynopus </i>(anura: terrarana: craugastoridae) from río abiseo national park, peru.we describe four new species of terrestrial-breeding frogs belonging to the genus phrynopus from specimens collected on the eastern slopes of the cordillera oriental (2800-3850 m) near and within río abiseo national park, provincia mariscal cáceres, departments of san martín and la libertad, northeastern peru. all four species lack a visible tympanum and inhabit the upper ridges and slopes within or adjacent to the park. phrynopus anancites sp. nov. and p. capitalis sp. nov. inhabit the wet mont ...201728610240
population dynamics of the critically endangered toad atelopus cruciger and the fungal disease chytridiomycosis.harlequin toads (atelopus) are among the most severely impacted amphibians by the emergence of chytridiomycosis, a fungal disease caused by the pathogen batrachochytrium dendrobatidis (bd). many species disappeared while others suffered drastic contractions of their geographic distribution to lower altitudes. a diminished virulence of bd in warm habitats was proposed to explain the survival of lowland populations of harlequin toads (i.e. thermal refuge hypothesis). to understand the mechanisms t ...201728570689
introduced bullfrogs are associated with increased batrachochytrium dendrobatidis prevalence and reduced occurrence of korean treefrogs.bullfrogs, lithobates catesbeianus, have been described as major vectors of the amphibian chytrid fungus, batrachochytrium dendrobatidis (bd). bd is widespread throughout the range of amphibians yet varies considerably within and among populations in prevalence and host impact. in our study, the presence of l. catesbeianus is correlated with a 2.5 increase in bd prevalence in treefrogs, and the endangered dryophytes suweonensis displays a significantly higher bd prevalence than the more abundant ...201728562628
batrachochytrium dendrobatidis is present in poland and associated with reduced fitness in wild populations of pelophylax lessonae.the fungus batrachochytrium dendrobatidis (bd) is a pathogen associated with global declines of amphibians. we used qpcr to detect bd in 255 samples from 10 polish populations of 8 species. we found bd infection in 3 species (bombina variegata, pelophylax lessonae, p. esculentus). the infection intensity in p. lessonae reached a maximum of 58400 genomic equivalents of zoospores (ge), and the 2 most heavily infected individuals died. previous observations of the populations that included infected ...201728492180
virulence variation among strains of the emerging infectious fungus batrachochytrium dendrobatidis (bd) in multiple amphibian host species.emerging infectious diseases have been documented in numerous plant and animal populations. the infectious disease amphibian chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd), is associated with global amphibian population declines. while much bd-amphibian research has centered on response variation in hosts, a paucity of information exists on how variation in the pathogen, such as strain differences, affects infection dynamics. to examine how different bd strains may di ...201728492179
using a bayesian network to clarify areas requiring research in a host-pathogen system.bayesian network analyses can be used to interactively change the strength of effect of variables in a model to explore complex relationships in new ways. in doing so, they allow one to identify influential nodes that are not well studied empirically so that future research can be prioritized. we identified relationships in host and pathogen biology to examine disease-driven declines of amphibians associated with amphibian chytrid fungus (batrachochytrium dendrobatidis). we constructed a bayesia ...201728464282
cryptic chytridiomycosis linked to climate and genetic variation in amphibian populations of the southeastern united states.north american amphibians have recently been impacted by two major emerging pathogens, the fungus batrachochytrium dendrobatidis (bd) and iridoviruses in the genus ranavirus (rv). environmental factors and host genetics may play important roles in disease dynamics, but few studies incorporate both of these components into their analyses. here, we investigated the role of environmental and genetic factors in driving bd and rv infection prevalence and severity in a biodiversity hot spot, the south ...201728448517
minimum lethal concentration of sodium hypochlorite for the amphibian pathogen batrachochytrium dendrobatidis.sodium hypochlorite (naocl) is the active ingredient in household bleach and is commonly used as a disinfectant to clean equipment contaminated by the amphibian pathogen batrachochytrium dendrobatidis (bd) in lab husbandry and field studies. we conducted a series of replicated exposure trials using a single global pandemic lineage bd isolate from panama (jel 310) and concentrations of naocl ranging from 0.006% to 0.6% for exposure times ranging from 30 seconds to 15 minutes to determine the mini ...201728441417
batrachochytrium dendrobatidis and the decline and survival of the relict leopard frog.epizootic disease caused by the fungal pathogen batrachochytrium dendrobatidis (bd) is a major driver of amphibian declines, yet many amphibians declined before the pathogen was described. the relict leopard frog, rana onca (=lithobates onca), was nearly extinct, with the exception of populations within a few geothermal springs. growth of bd, however, is limited by high water temperature, and geothermal springs may have provided refuge during outbreaks of chytridiomycosis. we conducted field sur ...201728439781
chytrid fungus infection in zebrafish demonstrates that the pathogen can parasitize non-amphibian vertebrate hosts.aquatic chytrid fungi threaten amphibian biodiversity worldwide owing to their ability to rapidly expand their geographical distributions and to infect a wide range of hosts. combating this risk requires an understanding of chytrid host range to identify potential reservoirs of infection and to safeguard uninfected regions through enhanced biosecurity. here we extend our knowledge on the host range of the chytrid batrachochytrium dendrobatidis by demonstrating infection of a non-amphibian verteb ...201728425465
spatial distribution of batrachochytrium dendrobatidis in south american caecilians.the amphibian-killing fungus batrachochytrium dendrobatidis (bd) is linked to population declines in anurans and salamanders globally. to date, however, few studies have attempted to screen bd in live caecilians; bd-positive caecilians have only been reported in africa and french guiana. here, we performed a retrospective survey of museum preserved specimens to (1) describe spatial patterns of bd infection in gymnophiona across south america and (2) test whether areas of low climatic suitability ...201728425424
diversity in growth patterns among strains of the lethal fungal pathogen batrachochytrium dendrobatidis across extended thermal optima.the thermal sensitivities of organisms regulate a wide range of ecological interactions, including host-parasite dynamics. the effect of temperature on disease ecology can be remarkably complex in disease systems where the hosts are ectothermic and where thermal conditions constrain pathogen reproductive rates. amphibian chytridiomycosis, caused by the pathogen batrachochytrium dendrobatidis (bd), is a lethal fungal disease that is influenced by temperature. however, recent temperature studies h ...201728424893
accuracy of climate-based forecasts of pathogen spread.species distribution models (sdms) are a tool for predicting the eventual geographical range of an emerging pathogen. most sdms, however, rely on an assumption of equilibrium with the environment, which an emerging pathogen, by definition, has not reached. to determine if some sdm approaches work better than others for modelling the spread of emerging, non-equilibrium pathogens, we studied time-sensitive predictive performance of sdms for batrachochytrium dendrobatidis, a devastating infectious ...201728405387
amphibian skin microbiota exhibits temporal variation in community structure but stability of predicted bd-inhibitory function.host-associated microbiomes are increasingly recognized to contribute to host disease resistance; the temporal dynamics of their community structure and function, however, are poorly understood. we investigated the cutaneous bacterial communities of three newt species, ichthyosaura alpestris, lissotriton vulgaris and triturus cristatus, at approximately weekly intervals for 3 months using 16s ribosomal rna amplicon sequencing. we hypothesized cutaneous microbiota would vary across time, and that ...201728387770
fight fungi with fungi: antifungal properties of the amphibian mycobiome.emerging infectious diseases caused by fungal taxa are increasing and are placing a substantial burden on economies and ecosystems worldwide. of the emerging fungal diseases, chytridomycosis caused by the fungus batrachochytrium dendrobatidis (hereafter bd) is linked to global amphibian declines. amphibians have innate immunity, as well as additional resistance through cutaneous microbial communities. despite the targeting of bacteria as potential probiotics, the role of fungi in the protection ...201729312201
host size influences the effects of four isolates of an amphibian chytrid fungus.understanding factors that influence host-pathogen interactions is key to predicting outbreaks in natural systems experiencing environmental change. many amphibian population declines have been attributed to an amphibian chytrid fungus, batrachochytrium dendrobatidis (bd). while this fungus is widespread, not all bd-positive populations have been associated with declines, which could be attributed to differences in pathogen virulence or host susceptibility. in a laboratory experiment, we examine ...201729187961
culture media and individual hosts affect the recovery of culturable bacterial diversity from amphibian skin.one current challenge in microbial ecology is elucidating the functional roles of the large diversity of free-living and host-associated bacteria identified by culture-independent molecular methods. importantly, the characterization of this immense bacterial diversity will likely require merging data from culture-independent approaches with work on bacterial isolates in culture. amphibian skin bacterial communities have become a recent focus of work in host-associated microbial systems due to th ...201728883811
genomic epidemiology of the emerging pathogen batrachochytrium dendrobatidis from native and invasive amphibian species in chile.emerging fungal diseases represent a threat to food security, animal and human health worldwide. amphibian chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd), has been associated with catastrophic and well-documented amphibian population declines and extinctions. for the first time, bd was cultured from native and non-native wild amphibians in chile. phylogenomic analyses revealed that chilean isolates avs2, avs4 and avs7 group within the global panzootic lineage of bd (b ...201729205924
fragile coexistence of a global chytrid pathogen with amphibian populations is mediated by environment and demography.unravelling the multiple interacting drivers of host-pathogen coexistence is crucial in understanding how an apparently stable state of endemism may shift towards an epidemic and lead to biodiversity loss. here, we investigate the apparent coexistence of the global amphibian pathogen batrachochytrium dendrobatidis (bd) with bombina variegata populations in the netherlands over a 7-year period. we used a multi-season mark-recapture dataset and assessed potential drivers of coexistence (individual ...201728978729
dietary carotenoid supplementation enhances the cutaneous bacterial communities of the critically endangered southern corroboree frog (pseudophryne corroboree).the rapid spread of infectious disease has resulted in the decline of animal populations globally. amphibians support a diversity of microbial symbionts on their skin surface that help to inhibit pathogen colonisation and reduce disease susceptibility and virulence. these cutaneous microbial communities represent an important component of amphibian immune defence, however, very little is known about the environmental factors that influence the cutaneous microbiome. here, we characterise the cuta ...201727623966
antifungal efficacy of f10sc veterinary disinfectant against batrachochytrium dendrobatidis.the infectious disease chytridiomycosis, which is caused by the fungal pathogen batrachochytrium dendrobatidis, has been identified as one of the most important drivers of amphibian declines and extinction. in vitro b. dendrobatidis is susceptible to a range of disinfectants, but not all have been tested on animals and some that have been proven effective have harmful side effects on the surrounding environment or the animals being treated. we tested the efficacy of f10sc veterinary disinfectant ...201728371902
unlocking the story in the swab: a new genotyping assay for the amphibian chytrid fungus batrachochytrium dendrobatidis.one of the most devastating emerging pathogens of wildlife is the chytrid fungus, batrachochytrium dendrobatidis (bd), which affects hundreds of amphibian species around the world. genomic data from pure bd cultures has advanced our understanding of bd phylogenetics, genomic architecture, and mechanisms of virulence. however pure cultures are laborious to obtain and whole genome sequencing is comparatively expensive, so relatively few isolates have been genetically characterized. thus we still k ...201728371384
evidence of batrachochytrium dendrobatidis infection in amphibians from serbian lowlands.we investigated presence of batrachochytrium dendrobatidis in the republic of serbia. seven out of 88 samples (8%) tested positive, all belonging to the frog genus pelophylax. two positive sites were located directly on the danube river. the danube river could be an important disease corridor, and distribution of batrachochytrium dendrobatidis along this river should be further explored.201728368677
complex interactive effects of water mold, herbicide, and the fungus batrachochytrium dendrobatidis on pacific treefrog hyliola regilla hosts.infectious diseases pose a serious threat to global biodiversity. however, their ecological impacts are not independent of environmental conditions. for example, the pathogenic fungus batrachochytrium dendrobatidis (bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. we examined the combined ...201728322209
prevalence and pathogen load estimates for the fungus batrachochytrium dendrobatidis are impacted by its dna copy number variation.the ribosomal gene complex is a multi-copy region that is widely used for phylogenetic analyses of organisms from all 3 domains of life. in fungi, the copy number of the internal transcribed spacer (its) is used to detect abundance of pathogens causing diseases such as chytridiomycosis in amphibians and white nose syndrome in bats. chytridiomycosis is caused by the fungi batrachochytrium dendrobatidis (bd) and b. salamandrivorans (bsal), and is responsible for declines and extinctions of amphibi ...201728322208
characterization of batrachochytrium dendrobatidis inhibiting bacteria from amphibian populations in costa rica.global amphibian declines and extinction events are occurring at an unprecedented rate. while several factors are responsible for declines and extinction, the fungal pathogen batrachochytrium dendrobatidis (bd) has been cited as a major constituent in these events. while the effects of this chytrid fungus have been shown to cause broad scale population declines and extinctions, certain individuals and relict populations have shown resistance. this resistance has been attributed in part to the cu ...201728293222
batrachochytrium salamandrivorans is the predominant chytrid fungus in vietnamese salamanders.the amphibian chytrid fungi, batrachochytrium dendrobatidis (bd) and b. salamandrivorans (bsal), pose a major threat to amphibian biodiversity. recent evidence suggests southeast asia as a potential cradle for both fungi, which likely resulted in widespread host-pathogen co-existence. we sampled 583 salamanders from 8 species across vietnam in 55 locations for bsal and bd, determined scaled mass index as a proxy for fitness and collected environmental data. bsal was found within 14 of the 55 hab ...201728287614
effects of corticosterone on infection and disease in salamanders exposed to the amphibian fungal pathogen batrachochytrium dendrobatidis.although it is well established that glucocorticoid hormones (gcs) alter immune function and disease resistance in humans and laboratory animal models, fewer studies have linked elevated gcs to altered immune function and disease resistance in wild animals. the chytrid fungal pathogen batrachochytrium dendrobatidis (bd) infects amphibians and can cause the disease chytridiomycosis, which is responsible for worldwide amphibian declines. it is hypothesized that long-term exposure to environmental ...201728262636
long-term monitoring of tropical alpine habitat change, andean anurans, and chytrid fungus in the cordillera vilcanota, peru: results from a decade of study.the cordillera vilcanota in southern peru is the second largest glacierized range in the tropics and home to one of the largest high-alpine lakes, sibinacocha (4,860 m). here, telmatobius marmoratus (marbled water frog), rhinella spinulosa (andean toad), and pleurodema marmoratum (marbled four-eyed frog) have expanded their range vertically within the past century to inhabit newly formed ponds created by ongoing deglaciation. these anuran populations, geographically among the highest (5,200-5,40 ...201728261462
impact of asynchronous emergence of two lethal pathogens on amphibian assemblages.emerging diseases have been increasingly associated with population declines, with co-infections exhibiting many types of interactions. the chytrid fungus (batrachochytrium dendrobatidis) and ranaviruses have extraordinarily broad host ranges, however co-infection dynamics have been largely overlooked. we investigated the pattern of co-occurrence of these two pathogens in an amphibian assemblage in serra da estrela (portugal). the detection of chytridiomycosis in portugal was linked to populatio ...201728240267
amphibian immunity-stress, disease, and climate change.like all other vertebrate groups, amphibian responses to the environment are mediated through the brain (hypothalamic)-pituitary-adrenal/interrenal (hpa/i) axis and the sympathetic nervous system. amphibians are facing historically unprecedented environmental stress due to climate change that will involve unpredictable temperature and rainfall regimes and possible nutritional deficits due to extremes of temperature and drought. at the same time, amphibians in all parts of the world are experienc ...201727387153
greater species richness of bacterial skin symbionts better suppresses the amphibian fungal pathogen batrachochytrium dendrobatidis.the symbiotic microbes that grow in and on many organisms can play important roles in protecting their hosts from pathogen infection. while species diversity has been shown to influence community function in many other natural systems, the question of how species diversity of host-associated symbiotic microbes contributes to pathogen resistance is just beginning to be explored. understanding diversity effects on pathogen resistance could be particularly helpful in combating the fungal pathogen b ...201728064360
effects of amphibian phylogeny, climate and human impact on the occurrence of the amphibian-killing chytrid fungus.chytridiomycosis, due to the fungus batrachochytrium dendrobatidis (bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. because conservation programs are implemented locally, it is essential to understand how the complex interactions among host species, climate and human activities contribute to bd occurrence at regional scales. using weighted phylogenetic regressions and model selection, we investigated geographic patterns of bd occurrence along a l ...201728055125
disassembly of a tadpole community by a multi-host fungal pathogen with limited evidence of recovery.emerging infectious diseases can cause host community disassembly, but the mechanisms driving the order of species declines and extirpations following a disease outbreak are unclear. we documented the community disassembly of a neotropical tadpole community during a chytridiomycosis outbreak, triggered by the generalist fungal pathogen, batrachochytrium dendrobatidis (bd). within the first 11 months of bd arrival, tadpole density and occupancy rapidly declined. species rarity, in terms of tadpol ...201728052493
characterization of mhc class ia in the endangered southern corroboree frog.southern corroboree frogs (pseudophryne corroboree) have declined to near extinction in the wild after the emergence of the amphibian chytrid fungus batrachochytrium dendrobatidis in southeastern australia in the 1980s. a major captive breeding and reintroduction program is underway to preserve this iconic species, but improving resistance to b. dendrobatidis would help the wild population to be self-sustaining. using 3' and 5' rapid amplification of complementary dna ends (race), we characteriz ...201728028562
effect of simultaneous amphibian exposure to pesticides and an emerging fungal pathogen, batrachochytrium dendrobatidis.amphibian declines have been linked to numerous factors, including pesticide use and the fungal pathogen batrachochytrium dendrobatidis (bd). moreover, research has suggested a link between amphibian sensitivity to bd and pesticide exposure. we simultaneously exposed postmetamorphic american toads (anaxyrus americanus), western toads (a. boreas), spring peepers (pseudacris crucifer), pacific treefrogs (p. regilla), leopard frogs (lithobates pipiens), and cascades frogs (rana cascadae) to a facto ...201728001054
tracking the amphibian pathogens batrachochytrium dendrobatidis and batrachochytrium salamandrivorans using a highly specific monoclonal antibody and lateral-flow technology.the fungus batrachochytrium dendrobatidis (bd) causes chytridiomycosis, a lethal epizootic disease of amphibians. rapid identification of the pathogen and biosecurity is essential to prevent its spread, but current laboratory-based tests are time-consuming and require specialist equipment. here, we describe the generation of an igm monoclonal antibody (mab), 5c4, specific to bd as well as the related salamander and newt pathogen batrachochytrium salamandrivorans (bsal). the mab, which binds to a ...201727995742
recent emergence of a chytrid fungal pathogen in california cascades frogs (rana cascadae).the pathogenic fungus batrachochytrium dendrobatidis (bd) has been associated with global amphibian declines, but it is often difficult to discern the relative importance of bd as a causal agent in declines that have already occurred. retrospective analyses of museum specimens have allowed researchers to associate the timing of bd arrival with the timing of past amphibian declines. cascades frogs (rana cascadae) have experienced dramatic declines in northern california, but it is not clear wheth ...201727957606
environmental fluctuations and host skin bacteria shift survival advantage between frogs and their fungal pathogen.fluctuating environments can modulate host-pathogen interactions by providing a temporary advantage to one of the interacting organisms. however, we know very little about how environmental conditions facilitate beneficial interactions between hosts and their microbial communities, resulting in individual persistence with a particular pathogen. here, we experimentally infected eleutherodactylus coqui frogs with the fungal pathogen batrachochytrium dendrobatidis (bd) under environmental condition ...201727935596
what is your diagnosis? skin scraping from a hellbender. 201727870070
first in vivo batrachochytrium dendrobatidis transcriptomes reveal mechanisms of host exploitation, host-specific gene expression, and expressed genotype shifts.for generalist pathogens, host species represent distinct selective environments, providing unique challenges for resource acquisition and defense from host immunity, potentially resulting in host-dependent differences in pathogen fitness. gene expression modulation should be advantageous, responding optimally to a given host and mitigating the costs of generalism. batrachochytrium dendrobatidis (bd), a fungal pathogen of amphibians, shows variability in pathogenicity among isolates, and within- ...201727856699
antifungal bacteria on woodland salamander skin exhibit high taxonomic diversity and geographic variability.diverse bacteria inhabit amphibian skin, some of which inhibit growth of the fungal pathogen, batrachochytrium dendrobatidis (bd). yet, there has been no systematic survey of anti-bd bacteria across localities, species and elevations. this is important given geographic and taxonomic variation in amphibian susceptibility to bd. our sites were within the appalachian mountains where previous sampling indicated low bd prevalence. we determined the number and identity of anti-bd bacteria on 61 pletho ...201728213545
historical amphibian declines and extinctions in brazil linked to chytridiomycosis.the recent increase in emerging fungal diseases is causing unprecedented threats to biodiversity. the origin of spread of the frog-killing fungus batrachochytrium dendrobatidis (bd) is a matter of continued debate. to date, the historical amphibian declines in brazil could not be attributed to chytridiomycosis; the high diversity of hosts coupled with the presence of several bd lineages predating the reported declines raised the hypothesis that a hypervirulent bd genotype spread from brazil to o ...201728179514
no evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads.the parasitic chytrid fungus batrachochytrium dendrobatidis (bd) can cause the lethal disease chytridiomycosis in amphibians and therefore may play a role in population declines. the yellow-bellied toad bombina variegata suffered strong declines throughout western and northwestern parts of its range and is therefore listed as highly endangered for germany and the federal state of hesse. whether chytridiomycosis may play a role in the observed local declines of this strictly protected anuran spec ...201728177293
the thermal mismatch hypothesis explains host susceptibility to an emerging infectious disease.parasites typically have broader thermal limits than hosts, so large performance gaps between pathogens and their cold- and warm-adapted hosts should occur at relatively warm and cold temperatures, respectively. we tested this thermal mismatch hypothesis by quantifying the temperature-dependent susceptibility of cold- and warm-adapted amphibian species to the fungal pathogen batrachochytrium dendrobatidis (bd) using laboratory experiments and field prevalence estimates from 15 410 individuals in ...201728111904
variation in metabolite profiles of amphibian skin bacterial communities across elevations in the neotropics.both the structure and function of host-associated microbial communities are potentially impacted by environmental conditions, just as the outcomes of many free-living species interactions are context-dependent. many amphibian populations have declined around the globe due to the fungal skin pathogen, batrachochytrium dendrobatidis (bd), but enivronmental conditions may influence disease dynamics. for instance, in panamá, the most severe bd outbreaks have occurred at high elevation sites. some a ...201728105509
linking ecology and epidemiology to understand predictors of multi-host responses to an emerging pathogen, the amphibian chytrid fungus.variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. the fungal pathogen, batrachochytrium dendrobatidis (bd) has been detected in almost 700 different amphibian species and is implicated in numerous global amphibian population declines. identifying key hosts in the amphibian-bd system-those who are a ...201728095428
detection of the amphibian chytrid fungus batrachochytrium dendrobatidis in museum specimens of andean aquatic birds: implications for pathogen dispersal.the occurrence of the pathogenic chytrid fungus batrachochytrium dendrobatidis (bd) in the feet of live waterfowl has been documented, but the potential role of birds as dispersers has not been studied. we report the presence of bd in the feet of preserved aquatic birds in the bolivian high andes during the time of drastic amphibian declines in the country. we sampled 48 aquatic birds from the bolivian andes that were preserved in museum collections. birds were sampled for the presence of bd dna ...201728094607
a model to inform management actions as a response to chytridiomycosis-associated decline.decision-analytic models provide forecasts of how systems of interest will respond to management. these models can be parameterized using empirical data, but sometimes require information elicited from experts. when evaluating the effects of disease in species translocation programs, expert judgment is likely to play a role because complete empirical information will rarely be available. we illustrate development of a decision-analytic model built to inform decision-making regarding translocatio ...201727056609
exposure to corticosterone affects host resistance, but not tolerance, to an emerging fungal pathogen.host responses to pathogens include defenses that reduce infection burden (i.e., resistance) and traits that reduce the fitness consequences of an infection (i.e., tolerance). resistance and tolerance are affected by an organism's physiological status. corticosterone ("cort") is a hormone that is associated with the regulation of many physiological processes, including metabolism and reproduction. because of its role in the stress response, cort is also considered the primary vertebrate stress h ...201727690360
does physiological response to disease incur cost to reproductive ecology in a sexually dichromatic amphibian species?it is well known that the disease chytridiomycosis, caused by the fungal pathogen batrachochytrium dendrobatidis (bd) has contributed to amphibian declines worldwide. the impact of bd varies, with some species being more susceptible to infection than others. recent evidence has shown that bd can have sub-lethal effects, whereby increases in stress hormones have been associated with infection. could this increased stress response, which is a physiological adaptation that provides an increased res ...201727712921
evolution of resistance to chytridiomycosis is associated with a robust early immune response.potentiating the evolution of immunity is a promising strategy for addressing biodiversity diseases. assisted selection for infection resistance may enable the recovery and persistence of amphibians threatened by chytridiomycosis; a devastating fungal skin disease threatening hundreds of species globally. however, knowledge of the mechanisms involved in the natural evolution of immunity to chytridiomycosis is limited. understanding the mechanisms of such resistance may help speed assisted-select ...201829337419
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